The first one to two minutes after starting a cold engine are decisive for the emission of pollutants from an internal combustion engine.
In this time approximately 70-80% of the total emission of HC and CO are discharged. Since the catalytic converter has not reached its operating temperature during this time interval, the engine discharges almost the crude emission products without catalytic conversion.
Various means are known for reducing the emissions, for example, by heating the catalytic converter with a burner system (as disclosed in DE-A2,219,371).
A secondary air system is disclosed in the Pierburg product information brochure "Electric Secondary Air Pump" No. 5/4 00-151 01, 9/91, published at the International Automobile Exhibition, Frankfurt/Main, 1991, which provides for the intake of secondary air into the exhaust manifold during the cold phase, when the catalytic converter of the internal combustion engine is not yet operative.
In this way, the pollutants CO and HC, which are formed in the cold phase due to an engine-side air index of lambda &lt;1, are reduced, and heat is introduced into the catalytic converter for obtaining a more rapid operation-ready state after the cold start. The secondary air intake system consists of an air pump, one or more check valves and a cut-off valve.
In order to achieve operation readiness still more rapidly, in connection with this secondary air system, a process is disclosed in unpublished Patent Application DE-P41 32 814 A1, in which the catalytic converter is heated by a burner operating with the fuel of the internal combustion engine, and air for combustion is supplied to the burner system, by an air pump of the secondary air system.
Depending on the field of application of a burner system in the exhaust and/or intake system of an internal combustion engine, various requirements on the operating parameters exist, such as, for example, the pressure in the combustion chamber of the burner system, which may lead to an adverse influence on the burner function.